Arthritis is a major source of morbidity in the US population. Current treatment regimens are of limited efficacy, as there are no entirely non-toxic pharmaceuticals which totally halt or reverse the progression of joint injury. Post-treatment with a novel therapeutic, mercaptoethyguanidine (MEG), delivered by a parenteral route (i.p.), reverses inflammation and joint injury in a collagen-induced model of experimental arthritis. Inotek, Inc. now proposes: 1) to test whether enteral administration of MEG is similarly effective in a rat model of arthritis, and 2) to confirm that chronic enteral administration of MEG is non-toxic. Upon confirmation of efficacy and safety in this stringent and clinically relevant model, Inotek intends to apply for Phase 2 SBIR funding to support formal toxicology studies and a Phase 1 FDA-regulated clinical trial. PROPOSED COMMERCIAL APPLICATION: The commercial value of a potent anti-arthritic agent which would reverse, rather than prevent the development of joint injury is enormous. Conservative estimates place the market size in the US alone at greater than 1 billion dollars per annum.